The long-standing Peccei-Quinn mechanism remains the favored
explanation for the absence of CP-violation in QCD. The concomitant
axion, a very low-mass pseudoscalar particle, remains a favored
candidate for the cold dark matter of the universe. The first
full-scale axion dark matter experiment has begun to take data and
numerous new initiatives to search for axions with realistic
parameters have recently sprung up. The theoretical motivation for
axions, astrophysical limits, and the landscape of old and new
experimental opportunities will be explored.